Armor system having ceramic matrix composite layers

ABSTRACT

An example armor system includes a first ceramic matrix composite armor layer, a second ceramic matrix composite armor layer, and a monolithic ceramic armor layer directly bonded to the first and the second ceramic matrix composite armor layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 12/039,851, filed on 29 Feb. 2008, and Ser. No. 12/100,528, filed on 10 Apr. 2008; both of which are continuations-in-part of U.S. application Ser. No. 11/682,390, filed 6 Mar. 2007, which claims priority to U.S. Provisional Application No. 60/794,276. This application also claims priority to U.S. Provisional Application No. 61/423,811, which was filed on 16 Dec. 2010. Each of these applications is incorporated herein by reference.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with government support under Contract No. W911QX-07-C-0077 awarded by the United States Army. The Government has certain rights in this invention.

BACKGROUND

This disclosure relates to an armor system and, more particularly, to an armor system having multiple ceramic and ceramic matrix composite layers and a method for manufacturing the armor system.

A variety of configurations of projectile resistant armor are known. Some are used on vehicles while others are specifically intended to protect an individual. Some materials or material combinations have proven useful for both applications. However, there is a continuing need to provide armor systems with lower aerial density, and methods of manufacturing armor systems that are useful in a variety of different applications.

SUMMARY

An example armor system includes a first ceramic matrix composite armor layer, a second ceramic matrix composite armor layer, and a monolithic ceramic armor layer directly bonded to the first and the second ceramic matrix composite armor layers without the use of a polymer based adhesive.

Another example armor system includes a first ceramic matrix composite armor layer, a second ceramic matrix composite armor layer, and a monolithic ceramic armor layer. The monolithic layer has a first side and an opposing, second side. The first side is directly bonded to the first ceramic matrix composite armor layer and free of any adhesive therebetween. The second side is directly bonded to the second ceramic matrix composite armor layer and free of any adhesive therebetween. A fibrous polymeric backing layer is directly bonded to the second ceramic matrix composite armor layer. The monolithic ceramic armor layer is silicon carbide in one example.

An example method of manufacturing an armor system includes forming a first ceramic matrix composite armor layer on a first side of a monolithic ceramic armor layer such that the first ceramic matrix composite armor layer is directly bonded to the monolithic ceramic armor layer and free of any adhesive therebetween. The method also includes forming a second ceramic matrix composite armor layer on an opposing, second side of the monolithic ceramic armor layer such that the second ceramic matrix composite layer is directly bonded to the monolithic ceramic armor layer and free of any adhesive therebetween. The first and second ceramic matrix composite armor layers each comprise a ceramic matrix and unidirectionally oriented fibers disposed within the ceramic matrix.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.

FIG. 1 illustrates an example armor system.

FIG. 2 illustrates a portion of an example ceramic matrix composite armor layer having unidirectionally oriented fibers disposed within a ceramic matrix.

FIG. 3 illustrates another example armor system.

FIG. 4 illustrates a 0°//90° ceramic matrix composite armor layer.

FIG. 5 illustrates a 0°/45°/90° ceramic matrix composite armor layer.

FIG. 6 illustrates armored panels utilized within an armor vest.

FIG. 7 illustrates an example method for manufacturing an armor system.

DETAILED DESCRIPTION

FIG. 1 illustrates a portion of an example armor system 10 for resisting impact of a ballistic projectile. The armor system 10 may be utilized in a variety of different applications for defeating ballistics, including, but not limited to, armor piercing projectiles at various velocities. For example, the armor system 10 includes an aerial density that is at least equal to or lighter than known armor systems and may be used as a plate or panel in a personal body armor vest or vehicle.

The armor system 10 is a multilayer structure that includes a monolithic ceramic armor layer 12, a ceramic matrix composite armor layer 13, another ceramic matrix composite armor layer 14, and a fibrous polymeric backing layer 15. It is to be understood that the ceramic armor layer 12, the ceramic matrix composite armor layers 13 and 14, and the fibrous polymeric backing layer 15 may also be used in combination with other armor layers, depending upon a particular design and intended use. The fibrous polymeric backing layer 15 is secured to the ceramic matrix composite armor layer 14.

The armor system 10 is arranged relative to an expected projectile direction 16. The ceramic matrix composite armor layer 13 includes a projectile strike face 18 for initially receiving a projectile 17, such as a bullet, which has a diameter d. The diameter d is a sometimes considered a caliber of the projectile 17. In this example, the diameter d is a measurement of the projectile 17 in a direction aligned with the strike face 18.

The ceramic armor layer 12 and ceramic matrix composite armor layers 13 and 14 may be any desired thickness or shape for resisting a ballistic impact. In some examples, the thickness is selected depending on the projectile 17. For example, the monolithic ceramic armor layer 12 and ceramic matrix composite armor layer 14 may be between several hundredths of an inch thick and several inches thick, depending upon a particular design and intended use of the armor system 10. In this example, the thickness t of the monolithic ceramic armor layer 12 is about 70 percent of the diameter d of the projectile 17. In another example, the thickness t is between 60 percent and 85 percent of the diameter d. In yet another example, the thickness t is between 80 percent and 85 percent of the diameter d. Further, in this example, the ceramic matrix composite layer 14 is about three times thicker than the ceramic matrix composite layer 13.

A front face 19 of the monolithic ceramic armor layer 12 is bonded to the ceramic matrix composite layer 13. A back face 20 of the ceramic armor layer 12, which opposes the front face 19, is bonded to the ceramic matrix composite armor layer 14. Thus, the ceramic armor layer 12 and the ceramic matrix composite armor layers 13 and 14 are directly bonded to one another, as will be described below, and do not necessarily include any layers of adhesive that would add thickness and/or diminish the ballistic impact performance of the armor system 10.

Using ceramic materials for the ceramic armor layer 12 and the ceramic matrix composite armor layers 13 and 14 provides a relatively close sound impedance match between the layers. Sound impedance refers to the speed of sound through a given ceramic layer of armor material. For example, an impact between a projectile and the projectile strike face 18 of the ceramic armor layer 12 causes compressive stress waves to move through the ceramic matrix composite armor layer 13, the monolithic ceramic armor layer 12, and the ceramic matrix composite armor layer 14 toward the back face 20. At least a portion of the compressive stress wave reflects off of a front face 18 of the ceramic matrix composite armor layer 13, a rear face 23 of the ceramic matrix composite layer 13, the back face 20 of the ceramic layer 12, and a rear face 24 of the ceramic matrix composite armor layer 14.

In prior art, the stress waves passing through the monolithic ceramic encounters either an adhesive, or the polymer matrix of a bonded polymer composite, at the backface. The sharp change in impedance, orders of magnitude lower than the monolithic ceramic, inherent in these polymer layers causes a high magnitude reflected tensile wave to return through the ceramic. Because monolithic ceramics are much weaker in tension than compression, this reflected tensile wave results in extensive damage and fracture.

In the embodiment of FIG. 1, the similar impedance of the monolithic ceramic armor layer 12 and matrix of the ceramic matrix composite layers 13 and 14 cause the incoming compressive pulse to be transmitted as a compressive wave that is rapidly and efficiently absorbed into ceramic matrix composite layers 13 or 14 which possess high work of fracture under tension and compression. This provides more efficient energy absorption that captures a greater fraction of the incoming compressive wave than in the prior art polymer adhesive bonded and/or polymer matrix composite layered armor.

Depending on the ceramic materials selected, the impedance of each of the ceramic armor layer 12 and the ceramic matrix composite armor layers 13 and 14 may be in the range of 10-40×10⁶ kilograms per square meter seconds (kg/m²s). In a further example, the impedance may be in the range of about 25-35×10⁶ kg/m²s.

In the disclosed embodiment, the ceramic armor layer 12 is a monolithic ceramic material. More specifically, the ceramic armor layer 12 is a material such as silicon carbide, or boron carbide. The impedance of this material may be in the range of 15-20 kilograms per square meter seconds (kg/m²s), which is relatively close to the impedance of the ceramic matrix composite armor layers 13 and 14.

The term “monolithic” as used in this disclosure refers to a single material; however, the single material may include impurities that do not affect the properties of the material, elements that are unmeasured or undetectable in the material, or additives (e.g., processing agents or densification aides). However, in other examples, the monolithic material may be pure and free of impurities. Given this description, one of ordinary skill in the art will understand that other oxides, carbides, nitrides, or other types of ceramics may be used to suit a particular need.

In the disclosed embodiment, the ceramic matrix composite armor layers 13 and 14 are a composite material. FIG. 2 illustrates a perspective view of the ceramic matrix composite armor layer 14, which includes a ceramic matrix 34 and unidirectionally oriented fibers 36 disposed within the ceramic matrix 34. That is, the unidirectionally oriented fibers 36 are substantially parallel and coplanar. The term “substantially” as used in this description relative to geometry refers to possible variation in the given geometry, such as typical manufacturing variation. The construction of the example ceramic composite armor layer 13 is similar to the construction of the ceramic composite armor layer 14 shown in FIG. 2.

The monolithic ceramic material of the ceramic armor layer 12 initially receives a ballistic projectile and absorbs a portion of the energy associated with the ballistic projectile through fracture and stress wave cancellation as described above. The composite of the ceramic matrix composite armor layer 14 reflects a portion of the stress waves as discussed above and absorbs a portion of the energy associated with the ballistic projectile through fiber debonding and pullout, as well as shear failure. The composite also facilitates reduction in the degree of fragmentation of the monolithic ceramic material compared to conventional backing materials.

In the disclosed examples, the unidirectionally oriented fibers 36 facilitate energy absorption and reflection of stress waves due to the ballistic impact. For example, during a ballistic event, interwoven fibers that are bent around each other must first straighten out prior to absorbing large levels of strain energy. The time that it takes for the bent fibers to straighten may increase the ballistic response time. However, the unidirectionally oriented fibers 36 are already straight and therefore do not require additional time for straightening as do interwoven fibers. Thus, using the unidirectionally oriented fibers 36 facilitates reduction of the reaction time of the ceramic armor composite layer 14 or in a ballistic event.

As will now be described, the ceramic matrix 34 and unidirectionally oriented fibers 36 of the ceramic matrix composite armor layers 13 and 14 may include a variety of different types of materials, which may be selected depending on a particular intended use. The selected materials are a ceramic matrix composite, a glass matrix composite, or some combination of these. For example, the unidirectionally oriented fibers 36 may be silicon carbide fibers, silicon nitride fibers, silicon-oxygen-carbon fibers, silicon-nitrogen-oxygen-carbon fibers, aluminum oxide fibers, silicon aluminum oxynitride fibers, aluminum nitride fibers, or carbon fibers. In some examples, the unidirectionally reinforced fibers 36 include fibers of NICALON®, SYLRAMIC®, TYRANNO®, HPZ™, pitch derived carbon, or polyacronitrile derived carbon, fibers. Notably, these materials are not polymer matrix composite materials.

The ceramic matrix 34 may include a silicate glass material, such as magnesium aluminum silicate, magnesium barium silicate, lithium aluminum silicate, borosilicate, or barium aluminum silicate. Given this description, one of ordinary skill in the art will understand that other types of fibers and matrix materials may be used to suit a particular need.

As can be appreciated, the ceramic matrix composite armor layers 13 and 14 of FIG. 2 are each a single layer. In another embodiment illustrated in FIG. 3, like elements are represented with like reference numerals and modified elements are represented with the addition of a prime symbol. In this embodiment, an armor system 10′ includes ceramic matrix composite armor layers 13′ and 14′ each having a plurality of sublayers 38. Each of the sublayers 38 includes unidirectionally oriented fibers 36′ disposed within a matrix 34′, similar to the single layer of the ceramic matrix composite armor layers 13 and 14 of the previous example. Using multiple sublayers 38 may facilitate even greater energy absorption.

Each of the sublayers 38 may have an associated orientation relative to the unidirectionally oriented fibers 36′ of the respective sublayer 38. In this regard, the unidirectionally oriented fibers 36′ of the sublayers 38 may be arranged with different orientations to facilitate uniform energy absorption and reflection, for example. For instance, for illustrative purposes only, FIG. 4 illustrates only the unidirectionally oriented fibers 36′ of two of the sublayers 38. Unidirectionally oriented fibers 36′ of one of the sublayers 38 are oriented in a 0° orientation as represented by axis 40 and unidirectionally oriented fibers 36′ of another of the sublayers 38 are oriented 90° as represented by axis 44 relative to the 0° orientation 40. That is, the sublayers 38 provide a 0°/90° arrangement. As can be appreciated, the other sublayers 38 (including the sublayers 38 of the ceramic matrix composite layer 13′) may be likewise oriented.

In the disclosed example, six of the sublayers 38 are used in each of the ceramic matrix composite layers 13′ and 14′; however, fewer or more sublayers 38 may be used.

As can be appreciated, other orientations among the sublayers 38 may be used. FIG. 5 illustrates another example in which the unidirectionally oriented fibers 36′ of one of the sublayers 38 are oriented in a 0° orientation as represented by axis 46, unidirectionally oriented fibers 36′ of another sublayer 38 are oriented at a +45° orientation as represented by axis 48 relative to the 0° orientation 46, unidirectionally oriented fibers 36′ of another sublayer 38 are oriented at a −45° orientation as represented by axis 50 relative to the 0° orientation 46, and unidirectionally oriented fibers 36′ of another sublayer 38 are oriented at a 90° orientation as represented by axis 52 relative to the 0° orientation 46 (overall, a 0°/+45°/−45°/90° arrangement). Given this description, one of ordinary skill in the art will be able to recognize other orientations among the sublayers 38 to meet their particular needs.

Referring to FIG. 6, the armor system 10 or 10′ may be formed into panels 54 that are located within an armored vest 56. The panels 54 may be configured as small arms protective inserts (SAPI), which are removably retained at the front and the back of the armored vest 56. However, it is to be understood that the panels 54 may be sized to fit within current personal body armor system such as the interceptor body armor system. Additionally, the panels 54 may be adapted for use in other wearable armor systems for protecting an individual's side, neck, throat, shoulder, or groin areas.

FIG. 7 illustrates one example method for manufacturing the armor system 10 or 10′ into the shape of the panels 54 disclosed herein, or into other desired shapes. The manufacturing method 78 generally includes forming the ceramic matrix composite armor layers 13, 13′, 14 or 14′ using pre-impregnated unidirectionally oriented tape, although the disclosed armor systems 10 and 10′ are not limited to this manufacturing process and may be manufactured using other techniques.

The pre-impregnated unidirectionally oriented tape includes unidirectionally oriented fibers 36 or 36′ that are disposed within a glass-ceramic matrix particles 34 or 34′ before consolidation. That is, the ceramic matrix 34 or 34′ includes ceramic particles of the material selected for use as the ceramic matrix 34 or 34′ suspended in a binder, such as a polymeric binder.

The tape may be prepared from a slurry of the glass-ceramic particles in a carrier fluid, such as a solvent, and infiltrated into a fiber tow of the unidirectionally oriented fibers 36 or 36′. The infiltrated unidirectionally oriented fibers 36 or 36′ may then be dried to remove the carrier fluid from the slurry and thereby produce the pre-impregnated unidirectionally oriented tape.

Subsequently, the tape may be cut into sections and, in lay-up action 80, stacked with a desired orientation of the unidirectionally oriented fibers 36′. For the ceramic matrix composite armor layer 14 that utilizes only a single layer, only a single ply of the tape would be used. In a removal action 82, the binder is removed from the ceramic particles, such as by heating the tape at predetermined temperatures for predetermined amounts of time. The remaining green state composite is then consolidated in a consolidation action 84 at a predetermined temperature for a predetermined amount of time to produce the ceramic matrix composite armor layers 13, 13′, 14 or 14′.

In the disclosed embodiment, the glass-ceramic matrix composite armor layers 13, 13′, 14 or 14′ are consolidated or otherwise formed directly on the ceramic armor layer 12, which is pre-fabricated in a prior process. Forming the ceramic matrix composite armor layers 13, 13′, 14 or 14′ directly on the ceramic armor layer 12 facilitates providing a strong bond between the ceramic armor layer 12 and the matrix 34 or 34′ of the ceramic matrix composite armor layers 13, 13′, 14 or 14′. The relatively strong bonding may facilitate transmission of stress waves and absorption of energy as discussed above. For example, the ceramic matrix 34 or 34′ may chemically bond to the ceramic monolithic material of the ceramic armor layer 12. However, it is to be understood that any chemical bonding that may occur is not fully understood and may also comprise other reactions or mechanical interactions between the ceramic materials. In some examples, the consolidation action 84 of the example manufacturing method 78 may include other actions as disclosed in co-pending application Ser. No. 12/039,851.

Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims. 

I claim:
 1. An armor system, comprising: a first ceramic matrix composite armor layer; a second ceramic matrix composite armor layer; and a monolithic ceramic armor layer directly bonded to the first and the second ceramic matrix composite armor layers.
 2. The armor system of claim 1, wherein a first side of the monolithic ceramic armor layer is directly bonded to the first ceramic matrix composite armor layer, and an opposing, second side of the monolithic ceramic armor layer is bonded to the second ceramic matrix composite armor layer.
 3. The armor system of claim 1, wherein the armor system is free of any polymer or metal-based adhesive between the monolithic ceramic armor layer, the first ceramic matrix composite armor layer, and the second ceramic matrix composite armor layer.
 4. The armor system of claim 1, including a fibrous polymeric backing layer directly bonded to the second ceramic matrix composite armor layer.
 5. The armor system of claim 1, wherein the first ceramic matrix composite armor layer and the second ceramic matrix composite layer include a monolithic ceramic material selected from silicon nitride, silicon aluminum oxynitride, silicon carbide, silicon oxynitride, aluminum nitride, aluminum oxide, hafnium oxide, zirconia, siliconized silicon carbide, and boron carbide.
 6. The armor system of claim 1, wherein the first ceramic matrix composite armor layer, the second ceramic matrix composite armor layer, or both the first and second ceramic matrix composite armor layers comprise a ceramic matrix having a unidirectionally oriented fibers disposed within the ceramic matrix.
 7. The armor system of claim 6, wherein the unidirectionally oriented fibers are located within a plurality of sublayers of the ceramic matrix, and at least one of the plurality of sublayers includes unidirectionally oriented fibers having a different orientation than the unidirectionally oriented fibers of another of the plurality of sublayers.
 8. The armor system of claim 1, wherein the monolithic ceramic armor layer comprises a silicon carbide.
 9. The armor system of claim 8, wherein the silicon carbide is a hot-pressed silicon carbide.
 10. The armor system of claim 1, wherein the ceramic matrix composite armor layers consist of a matrix comprised of an alkaline earth aluminosilicate.
 11. The armor system of claim 1, wherein the armor system is configured to prevent a bullet from piercing the armor system, and a thickness of the monolithic ceramic armor layer is generally 70 percent of a caliber of the bullet.
 12. The armor system of claim 1, wherein the armor system is configured to prevent a projectile from piercing the armor system, and a thickness of the monolithic ceramic armor layer is between 60 percent and 85 percent of a diameter of the projectile.
 13. The armor system of claim 12, wherein the armor system is configured to prevent a projectile from piercing the armor system, and a thickness of the monolithic ceramic armor layer is between 80 percent and 85 percent of a diameter of the projectile.
 14. The armor system of claim 1, wherein the armor system is disposed within an armor panel that is located in at least one of portion of an armored vest or a vehicle.
 15. The armor system of claim 1, wherein at least one of the first or second ceramic matrix composite armor layers is a glass-ceramic matrix composite armor layer.
 16. An armor system, comprising: a first ceramic matrix composite armor layer; a second ceramic matrix composite armor layer; a monolithic ceramic armor layer having a first side and an opposing, second side, the first side directly bonded to the first ceramic matrix composite armor layer and free of any adhesive therebetween, the second side directly bonded to the second ceramic matrix composite armor layer and free of any adhesive therebetween; and a fibrous polymeric backing layer directly bonded to the second ceramic matrix composite armor layer.
 17. The armor system of claim 16, wherein at least one of the first or second ceramic matrix armor layer comprises a matrix consisting of an alkaline earth aluminosilicate.
 18. The armor system of claim 16, wherein the first ceramic matrix composite matrix armor layer and the second ceramic matrix composite armor layer each comprise a plurality of sub-layers that each include a ceramic matrix and unidirectionally oriented fibers disposed within the ceramic matrix, and at least one of the plurality of sub-layers having a different orientation than another of the sub-layers relative to the unidirectionally oriented fibers.
 19. A method of manufacturing an armor system, comprising: forming a first glass-ceramic matrix composite armor layer on a first side of a monolithic ceramic armor layer such that the first glass-ceramic matrix composite armor layer is directly bonded to the monolithic ceramic armor layer and free of any adhesive therebetween; and forming a second glass-ceramic matrix composite armor layer on an opposing, second side of the monolithic ceramic armor layer such that the second glass-ceramic matrix composite layer is directly bonded to the monolithic ceramic armor layer and free of any adhesive therebetween, wherein the first and second glass-ceramic matrix composite armor layers each comprise a ceramic matrix and unidirectionally oriented fibers disposed within the ceramic matrix.
 20. The method of claim 19, including forming a polyethylene fiber layer on a side of the second glass-ceramic matrix composite armor layer.
 21. The method of claim 19, wherein the matrix of the glass-ceramic armor layers are comprised of an alkaline earth aluminosilicate. 